Overview of currently approved veterinary vaccine potency testing methods and methods in development that do not require animal use

Veterinary vaccines must be safe, pure, potent, and effective. Potency tests help ensure that each consistently manufactured batch of vaccine provides a level of protection as determined in the original efficacy study throughout the products shelf life. Currently approved assays range from host animal vaccination and challenge to the quantification of specific protective antigens using in vitro technology. The development, maintenance, and update of in vitro potency assays continue to be a priority for both the animal health industry and the corresponding regulatory agencies. New assay development emphasis is being placed on assays that currently involve laboratory animal vaccination/challenge such as vaccines containing the Leptospira and Clostridium spp. antigens. This paper provides an overview of various in vitro potency assays available, the factors that can impact the accuracy of these methods, and specific considerations to be taken into account during assay development.